This invention relates to a printing apparatus. In particular, this invention relates to a novel design for a high speed web ink jet printing method and apparatus using multiple print heads to simultaneously print images on a roll of print media.
Thermal ink jet printers are well known and nearly ubiquitous among consumers who purchase and use personal computers in their home. More recently, improvements in thermal ink jet printing technology and improvements in the paper media used by these printers have yielded significant gains in image quality such that this technology is now used to print photo-quality images. It is anticipated that this technology will find use in commercial printing.
One drawback of a thermal ink jet printer, as well as piezo-electric electric ink jet printers, is the speed at which these machines are capable of producing images. At present, a single image is painted on the print media by a print head or group of printheads in a carriage assembly that repeatedly passes over or sweeps over the media, painting a line of multi-colored dots each time the printer carriage traverses the media surface. In such an operation, printing an image requires a significant amount of time. In an application where numerous images must be printed in a short time, such as in commercial printing, a single print head simply requires too much time to quickly print hundreds or even thousands of images a day.
A method and apparatus by which the throughput of an ink jet printer could be increased, particularly in commercial printing would be an improvement over the prior art.
A printer comprised of a paper delivery mechanism that moves paper beneath two or more ink jet printer carriages significantly increases the output rate of a thermal ink jet printer if multiple carriages are used to print several discrete images on a print media simultaneously. One printer carriage prints a first image on a first area of a print media while a second printer carriage prints a second image in a second area on the media while the first printer carriage prints the first image.